How to Choose Refractory Materials for Rotary Kiln

The rotary kiln is divided into a discharge end, a cooling zone, a firing zone, and a preheating zone from the kiln head end. The temperature in each section of the kiln ranges from 1000°C to 1350°C, and the requirements for refractory materials are also different. Refractory materials not only withstand high-temperature impact, but also withstand material corrosion, wear, and stress generated by kiln rotation. Therefore, there are strict requirements not only for the physical and chemical indicators of refractory materials.

1. Rotary kiln discharge port and cooling zone

Demand: Due to the joint action of high-temperature clinker, secondary air, and high-temperature flame, strong mechanical wear and chemical erosion are caused. Therefore, it is required to have good wear resistance, slag resistance, and thermal shock resistance.

Selection: Generally, first-grade high alumina bricks, thermal shock-resistant high alumina bricks, spinel bricks, chrome magnesia bricks, phosphate bricks, etc. are used as high alumina bricks, Refractory concrete (corundum aggregate), and silicon carbide bricks.

2. Rotary kiln firing zone

Purpose: The refractory layer fired in the rotary kiln is mainly subject to high-temperature impact and chemical corrosion (alkali corrosion). Therefore, magnesia bricks and chrome magnesia bricks should be selected as high-temperature refractory materials that are easy to hang in the kiln.

3. Rotary kiln transition zone (exothermic reaction zone)

Needs: The skin of the kiln is peeling off, the temperature changes frequently, the cylinder temperature is high, and the chemical corrosion is serious. This requires strong high-temperature impact resistance, low high-temperature flexural strength, and low elastic modulus. High-alumina bricks are made of corundum, combined with chrome-magnesia bricks, ordinary chrome-magnesia bricks, spinel bricks, etc.

4. Preheater and decomposition furnace

Requirements: Use refractory materials with high-temperature resistance and thermal insulation properties: the above-mentioned lower-temperature cyclone can be cast directly (refractory concrete). The following preheaters, decomposition furnaces, and connecting pipes can all be made of alkali-resistant clay bricks, and an insulation composite layer can be added. The ceiling is made of refractory bricks, backed by slag wool or castables. Castables are mostly used for each elbow. Dense semi-siliceous clay bricks can be used for the rising flue after the kiln to prevent alkali erosion.

5. Cement clinker cooler system

Refractory materials used in grid freezers include refractory bricks, lightweight cast bricks, high alumina insulating bricks, and insulation materials. Ordinary chrome magnesia bricks can be used in high-temperature areas, blanking throat areas, and high-temperature areas. Clay bricks can be used in medium and low-temperature areas.